Sanganna M. Sajjanar epub Studies on pollination potentiality of Indian honeybee (Apis cerana Fab.) on Ocimum kilimandscharicum Guerke and Ocimum gratissimum L.

The efficacy of .Indian honeybee (Apis cerana Fab.) in cross pollination of Ocimum kilimandscharicum Guerke and O. gratissimum L. was studied during summer of 2002 at Regional Research Station, University of Agricultural Sciences, GKVK Campus, Bangalore. Activity of different insect pollinators including honeybee species and Pollination influence of Indian honeybee on percent filled and unfilled seeds, seeds per fruit, seeds per inflorescence, test weight and inflorescence oil yield was studied. The quantity and quality of nectar from Ocimum flowers was also estimated to know its impact on foraging activity.At flowering, O. kilimandscharicum and O. gratissimum was visited by totally 20 insect species of which 18 belonged to the order Hymenoptera and two belonged to the order Diptera. Among the honeybee species in open condition, the activity of A. cerana was found highest (14.47 bees/plant/5min) compared to other bee species viz., A. florea, A. dorsata, T. iridipennis which showed an activity of 7.92, 7.48 and 3.46 bees/plant/5min on O. kilimandscharicum. Similarly, on O. gratissimum the activity of A. florea was highest (20.32 bees/plant/5min) compared to T. iridipennis, A. cerana, A. dorsata, which showed an activity of 8.93, 4.94 and 1.26 bees/plant/5min., respectively.In open condition, the peak pollen foraging activity of different species of honeybees was found between 1100- 1300 hr whereas, peak nectar foraging activity was found between 1000-1300 hr of the day in the course of study period on O. kilimandscharicum. Similarly, on O. gratissimum, the peak pollen foraging activity was found between 1000¬1100 hr and the nectar foraging activity was found between 1000-1400 hr of the day during the study period. Inside the cage, the peak pollen foraging activity of A. cerana was found at 1100 and 1000 hr and nectar foraging activity at 1000 hr on O. kilimandscharicum and O. gratissimum respectively.The pollen load carried by A. dorsata (20.28 and 19.18 mg) on O. kilimandscharicum and O. gratissimum was found to be significantly higher over other bees and the least pollen load was found in T. iridipennis (2.02 and 1.78 mg), respectively.The quantity and sugar concentration of the nectar was found higher in O. kilimandscharicum flowers (1.97 µl: 49.25%) than O. gratissimum (0.88 23.04%). The quantity and sugar concentration of the nectar was found to increase with the advancement of time up to 1400 hr, thereafter the sugar concentration of nectar decreased in both crops.The time spent by different species of honeybees in collection of pollen was found maximum between 0900-1000 hr. Among honeybees, in O. kilimandscharicum maximum mean time spent was recorded with T. iridipennis (18.4 sec/flower) followed by A. florea (13.8 sec/flower), A. cerana (10.0 sec/flower) and the least with A. dorsata (9.2 sec/flower). Similarly, on O. gratissimum, maximum time spent by different species of honeybees for pollen collection was recorded between 0900-1000 hr. Among the honeybees, maximum time spent was recorded with T. iridipennis (25.5 sec/flower) followed by A. florea (10.0 sec/flower), A. cerana (7.8 sec/flower) and the least with A. dorsata (6.5 sec/flower).In both the crops, significantly maximum percent filled seeds and test weight was found in open pollinated plots and lowest was found in control plots. The seed per fruit in open pollinated plots was on par with A. cerana pollinated plots. Whereas, seeds per fruit was significantly lower in control plots compared to open and A. cerana pollinated plots. Oil content and seeds per inflorescence in the open pollinated plots was on par with A. cerana pollinated plots. Whereas, in control plot, it was significantly lower compared to open and A. cerana pollinated plots.